Method of finishing the contact member



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1,405,049, Patented Jau. 31, 1922- UNITED STATES PATENT OFFICE.

FAYETTE LEISTER, OF PHILADELPHIA, PENNSYLVAITIA.

METHOD F FDISHING THE CONTACT MEIYIBER 0F A COMMUTATOR BRUSH;

Application led August 11, 1920.

specification.

In one process heretofore. employed in the manufacture of electrical contact members or elements for comn'lntatorI brushes, a mixture of copper, lead and graphite in known proportionsand in Agrnnu ated or powdered form-,hns been re ered-and requisite portions thereof ino d into the shape and form desired, these molded forms or parts being thereafter baked. It'hns been and is necessary after baking these parts to finish the same so :is-t0 'bring them to the exact dimensionsrequired' and also so as to provide 4an accurate and exact contact surface thereon lfor contacting with a commutator ring. Heretofore the finishing of these contact partshas been effected b the use of cutting and abrading tools. This methodof finishing these parts is expensive owin to the time 'required and, furthermore, foes not always provide `the smoothness and accuracy of finish desired.

Itis the object of my invention to rovide a process by the employment df w ich these partially completed contact ports or elements may be more economically finished into final form.

A further object of my invention is to provide a methodor process of finishing the said contact elements or parts in such manner that the surfaces thereof will not only bepolished and smooth but will be more con densed than is the case where the said parts or elements are finished or completed in accordance 4with the practice or method which heretofore has obtained and which at present obtains.

Although I have referred to only one proc ess or method heretofore employed in the manufacture of contact elements or parts for commutator brushes, it will be understood that the method employed by me for finishing such contact elements or parts is not limited by the method by or according to which these elements or parts are Shaped Specification of Letters Patent.

Patented Jan. 31, 1922.

serial No. insane. Y

or formed orto. the particular materials of which they consist.

The method embodying my invention may be employed in the finishing of` such contact elements, or parts Without regard to the method' or particular ingredients employed in theirv manufacture. i I

Other ob'ects and advantages of mylinvention wil be pointed out in the detailed description thereof which follows or will be :1p arent from such descri tion. l

n the accompanying rowing I have shown one formof device or npparatuslby the employment of which the method of ein .hodying my invention may be practised or carried out, bntit will lie understood that my invention is not limitedA t'o 'any particular' form of e paratus.

In the rawing: A, Y

Fig. 1 is a lonvitudinol, sectional view of a device adapt/edi for finishing n partially completed Contact element or part of n coininntator'brnsh itcoordin'u to my invention, the said' View being talien along the 'line 1-'-1 of Fig. 5; f. 'I

Fig. 2 i's a vertical 'sectionnlA view taken nt rivht :ingles to the View shown in Fig. l;

DFig. 3 is it longitudinal sectional view of the left hand portion of the device showing the completion of an operation; i

Fic'. 4 is' a vertical sectional view of the left 'hond' portion of thedevice taken Vat right angles to the view shown in Fig. 3;

F ig. 5 is a view in elevation of the right hond end of the die shown in section in Figs. l and 2, the double lines associated `with the openingr therethrouo'h indicating the different dimensions of the opening nt the receivY in r and delivery ends thereof;

ign 6 is a perspective View of the contact element ns shown in Figs. 1 :md 2 of the drawing before being finished according to my invention; and

Fig. 7 is a similar view showing the said Contact element or part after having been Finished in accordance with my invention.

Referring to the drawing: l and 2 desig nate the coo erating elements of a two-part die provide with an opening extending therethrough. The portion 3 of Suid opening from the receiving end thereof-to a transverse plane taken along the line 4 is tapered while the remaining portion 5 tothe lett of said ment of a commutator brush which comprises the steps oflaterally compressing the said element and causing simultaneous, relative movement between said element and the compressing means.

2. The method of finishing the contact element of a commutator brush which comprises the steps of laterally compressing the said element and causing simultaneous. sliding movement between the surface of said element and of the compressing means.

3. The method of finishing the contact element of a commutator brush which comprises the steps of compressing the same laterally and simultaneously polishing the sides thereof.

4. The method of manufacturing the contact element of a commutator brush which comprises the forming of the same to approximately the shape desired, and With dimensions slightly greater than the finished element`y thereafter gradually reducing the cross sectional area of said element by pressure, and finally applyin pressure to the contact portion of the e ement to form a contact surface thereon` 5. The method of manufacturing the contact element of a commutator brush which comprises the forming of the same to a proximately the shape desired, and with mensions greater than the finished element,

baking the same, thereafter gradually reducing the cross sectional area of said element by pressure, and finally applyin pressure to the contact element of said e emeiit to form a Contact surface thereon.

6, The method of finishing the contact e1e ment of a commutator brush which comprises laterally compressing the same to reduce the cross sectional area thereof, and thereafter subjecting one end thereof t0 pressure to form a concave-cylindrical contact surface therein.

7. The method of nishing the contact element of a commutator brush which comprises laterally compressing the same, smoothing and polishing the sides thereof simultaneously with the compressing action, and finally subjecting one end thereof to pressure to form a concave-cylindrical contact surface therein.

8. The method of forming the contact element of a commutator brush which comprises the forming thereof to a size sli htly larger than the finished element and t ereafter subjecting the same to lateral and axial pressures to finish it.

In testimoniy that I claim the foregoing as my invention, I have hereunto set my hand this 2nd day of August, 1920.

FAYETTE LEISTER. 

